LOS ANGELES — Rihanna's Last Girl on Earth tour may have been plagued by poor ticket sales during a bad summer for concerts, but fans were out in force at the tour's Los Angeles stop on Wednesday night. With sexy moves, a hint of violence and pyrotechnics, the singer delivered a nearly two-hour set (following opening sets from Travie McCoy and Ke$ha) that was capped by a surprise appearance by none other than Eminem.

The show began shortly after 7:30 p.m. as Gym Class Heroes frontman Travie McCoy hit the stage in support of his debut solo album, Lazarus. Tattooed from head to toe, wearing jeans, a T-shirt, suspender straps and a paperboy hat, he performed a quick 20-minute set as fans continued to trickle in and fill the arena. With a drummer, a DJ and a backdrop featuring his dog Stitch, McCoy strutted back and forth across the stage performing tracks including "The Manual," "Dr. Feel Good" and the summer hit "Billionaire" — sans Bruno Mars — before closing out by showing his softer (yet possibly still bitter) side with the breakup song "Need You."

Following McCoy was a wild, playful, foul-mouthed and at times sloppy Ke$ha, who emerged between two large lighting props shortly after 8 p.m. While echoes of "Right Round" filled the venue (the Flo Rida hit on which she's featured), the singer ordered everyone in the crowd to "Stand up right now!" Decked out in a black sequined short jumpsuit, a leopard bandana, sunglasses, fishnet hose, body glitter and a star painted on her left eye, the singer kicked off her performance, which as promised, provided nothing short of a full-fledged party vibe.

"I can't believe I am playing a show at the motherf---in' Staples Center!" the Animal singer exclaimed as she broke into "Blah, Blah, Blah." Accompanied by a full band and two quirky dancers, who at times where seen dancing in only American flag-designed Speedos, Ke$ha's set was a visual assault that included a gun-shaped guitar, exotic animal hats, cartwheels, drum smashing, and psychedelic cartoons that played on the stage behind her. She tore through six more songs from her debut album, including "Party at a Rich Dude's House," "Dinosaur," "Stephen," "Your Love Is My Drug," and finishing, of course, with the song that rocketed her to fame, "Tik-Tok."

After an hour-long intermission, the energy in the arena soared when Rihanna finally took the stage. Wasting no time, the singer opened up with her pop-rock ballad "Russian Roulette," wearing a floor-length black dress with flashing red lights while images of burning naked mannequins were displayed on screens behind her.

While stage lights flashed, six of her dancers emerged with glow-in-the-dark rifles. Rihanna reappeared shortly after, revealing a pink sequined bodysuit with her signature shoulder pads, which were a common theme throughout several of her outfit changes. Performing "Hard," the singer straddled a giant pink army tank with a Mickey Mouse army hat on while images of her video "Hard" flashed behind her.

Rihanna went on to perform a set filled with 23 hits, including "Disturbia," "Rehab," playful dance hits like "Pon de Replay," "Please Don't Stop the Music," and "S.O.S," and more intimate songs such as "Take a Bow" and "Hate That I Love You," and five different outfits, all of which had the similar leotard skin-tight looks that show off her figure. All the while, messages flashed across the screens, displaying statements that reflect Rihanna's dreamlike world: "One image. One voice. Welcome to Rihanna's world. The last girl on Earth."

Toward the end of the night, the crowd received the biggest treat of the show. As Rihanna began to sing the hook for "Love the Way You Lie," Eminem emerged from beneath the stage to join her. Allowing Eminem to take center stage, Rihanna gracefully stood nearby while the crowd screamed louder then ever. Dressed all in black, Eminem took control of the show and for an instant it almost appeared as if the crowd forgot they were attending a Rihanna show. But just as quickly as the song began, it was over, as the two disappeared beneath the stage together, leaving the audience chanting for more during the encore.

Closing out the night, Rihanna returned to play a medley of songs. As if to tease the audience into thinking another artist would make a guest appearance, she sang the hooks from "Live Your Life" and "Run This Town." The show ended with Rihanna's biggest hit song to date, "Umbrella," with red confetti released into the air, as she was elevated above the crowd on a platform. Once she was brought back onto the stage, she did a cute curtsy, thanking fans for making her dreams come true, before exiting the stage. As the lights came on, the dreamlike messages continued to flash up on the screen — "The dream is over. The dream is real" — while "What a Wonderful World" played throughout the arena.